Photo Gallery: U.S. Marine Protected Areas

Underwater archaeologists search for sunken ships, airplanes, and other clues from the past in the Papahānaumokuākea Marine National Monument in Hawai'i.

Nearly 140,000 square miles (360,000 square kilometers)—100 times the size of Yosemite National Park—the Papahānaumokuākea sanctuary was designated in 2006.

The park stretches 1,200 miles (1,900 kilometers) through the Pacific Ocean along Hawai'i's northwestern islands. It is home to the endangered Hawaiian monk seal and several species found nowhere else on Earth.